1. Field of the Invention
The present invention relates to the generation in a computor organ of musical sounds having "sliding" overtones that change in frequency as a function of time.
2. Description of the Prior Art
The history of electronic musical instruments has been relatively short when compared to the long periods during which "conventional" acoustic-type orchestral instruments have undergone their evolution to their present state. Electronic musical instrument development has understandably followed the obvious path of attempting to imitate or replicate the tone of the acoustic type of orchestral musical instruments. Thus, intensive efforts have been made to build electronic counter-parts of wind-blown organ pipes. These electronic instruments have been relatively successful because of some rather simple tonal characteristics of a wind-blown pipe. By adding various random noises and by careful control of the attack and release of a tone, very acceptable electronic organs have been designed. Fairly recently attempts have been made to obtain electronic instruments which imitate various orchestral-type musical instruments. It has been recognized that such electronic instruments must be capable of generating a wide variety of time variant tonal modulations instead of the simple on-off modulation of an organ-like tone. For lack of a better term, this new class of time variant modulation of tonal parameters has been given the generic name of "synthesizer" or "tone synthesizer".
An interesting by-product of the work on tone synthesizers is that there exists a wide variety of tonal effects which are definitely not imitative of conventional orchestral musical instruments. These tone effects have captured the fertile imagination of popular music musicians and have been used so effectively and frequently that these tonal effects now have found acceptance in orchestral groups.
An object of the present invention is to provide means for generating an entirely new family of synthesizer tones. These tones are all characterized by one or more overtones which may not be harmonically related to the fundamental and whose separation from the fundamental is time variant. Another object is to provide means for implementing such "sliding overtone" generation in an electronic musical instrument such as the computor organ disclosed in U.S. Pat. No. 3,809,786.